1. Field of the Invention
The present invention relates to medical devices, and, in particular, to a retractor for harvesting a blood vessel, which, in turn, is used in connection with an ongoing or subsequent surgical procedure. More particularly, the present invention provides such a retractor that is capable of defining and illuminating a subcutaneous working space to ameliorate accessibility to, and to facilitate visualization and harvesting of one or more blood vessels (e.g., radial artery, basilic vein) for grafting/transplantation in connection with a surgical procedure (e.g., coronary bypass surgery).
2. Description of Related Art
In certain surgical procedures, it is necessary to remove a portion (or even the entirety) of a patient's blood vessel for use in another, often remotely located part of that, or a different patient's body. For example, it is known to remove/excise some or all of a patient's radial artery, saphenous vein, cephalic vein, basilic vein or mammary artery for transplantation in connection with a coronary bypass surgical procedure. Once transplanted, the removed section (or entirety) of the vein/artery functions as a graft that replaces both the coronary arteries, which, as a result of aging and/or disease, have become blocked by plaque deposits, stenosis, or cholesterol, thus severely inhibiting their ability to supply life-sustaining blood to the patient's heart.
In some instances, these blockages can be treated with angioplasty, atherectomy or stent placement, and, therefore, coronary bypass surgery is not warranted. Quite often, however, a coronary bypass is required because these treatment methods are either contraindicated, or have proven incapable of removing blockages from coronary arteries.
According to current coronary bypass surgery techniques, a blood vessel is harvested from elsewhere within a patient's body and grafted into a locus between the patient's aorta and the coronary artery beyond the point of blockage. It is preferred to use a blood vessel taken from the patient undergoing bypass surgery, since he/she is a ready source of suitable vessels that will not be rejected by his/her own body after transplantation.
It has been found that each of a patient's radial or mammary artery, or saphenous, cephalic or basilic vein has functional and structural characteristics (e.g., diameter) resembling those of the coronary arteries, thus rendering any of these vessels potential candidates for grafting.
Among these vessels, however, the radial artery and the saphenous vein are often favored for transplantation in connection with coronary bypass surgery, likely due to the comparative ease of their harvesting and/or the comparative lack of complications (especially post-operative) associated with their harvesting and/or their subsequent transplantation.
Harvesting the saphenous vein entails making an incision in a patient's leg, and then pulling away layers of fatty tissue to reveal the saphenous vein, which is then carefully removed.
Until recently, the incision that was made to access the saphenous vein was quite long—spanning a patient's groin to at least his/her knee, and often to his/her ankle. Making this “fillet-like” incision inherently presents a serious risk of injury to the medial lymph bundle and/or to nerves located within the leg, as well as a realistic risk of infection to the incision site.
Moreover, the healing process associated with this long, “fillet-like” incision is protracted (often more prolonged than the incision(s) to the patient's chest in furtherance of the coronary bypass) and very painful, especially if the patient has circulation problems in his/her extremities. Ultimately, in fact, the incision often does not heal properly, thus requiring medical attention and/or invasive procedures (e.g., corrective surgery).
As indicated in U.S. Pat. No. 6,193,651 to DeFonzo, U.S. Pat. No. 6,228,025 to Hipps et al, and U.S. Pat. No. 6,322,499 to Evans et al., however, techniques now exist that allow the saphenous vein to be harvested by making several (usually either 2 or 3) smaller incisions on the proximal thigh, at the level of the knee joint, and, optionally, the inner malleolus.
In accordance with these techniques, a retractor is inserted into each of these incisions to define, access and illuminate the subcutaneous space. The retractor is used to form a skin bridge to allow for retraction of the fatty tissue surrounding the saphenous vein, which is then harvested.
Unfortunately, despite this advancement, many patients are not ideal candidates for saphenous vein harvesting by virtue of having an unacceptably high risk of minor to extensive complications associated with even these smaller leg incisions. Such patients include the elderly, the obese, diabetics, those who have developed extensive varicose veins in their legs, those who have fragile veins in their legs due to taking or having previously taken certain medications, and those whose saphenous vein is in a position that does not readily lend itself to harvesting.
These same patients, however, often are ideal candidates for other vessel harvesting options, such as radial artery harvesting, in which the radial artery is harvested from a patient's arm (usually his/her non-dominant arm). The radial artery is one of two arteries—the ulnar artery is the other—in a patient's forearm. Both these arteries stem from the brachial artery (the radial artery being the true continuation of the brachial artery) and, together, form a network of vessels, which supply blood to the wrist and hands, and which rejoin to form the palmar arch at the palm of the hand.
Radial artery harvesting is contraindicated in only a few classes of patients, such as those who have carpal tunnel syndrome, Raynaud's syndrome, and those who have severe kidney disease or poor blood circulation to their fingers.
Harvesting the radial artery for transplantation/grafting in connection with coronary bypass surgery historically involved making a continuous, “fillet-like” incision from approximately two inches below (i.e., toward the hand) the patient's elbow at the antecubital fossa to about one inch above (i.e., toward the elbow) the patient's wrist. The length of such an incision was reported, on average, to be about 23 cm (i.e., about 9 inches). A. Uchida et al., Endoscopic Harvesting of Radial Artery Graft for Coronary Artery Bypass, Ann. Plast. Surg. 1998; 41:459-463).
Just as making a “fillet-like” incision causes significant risks in the context of saphenous vein harvesting, making an approximately 23 cm (i.e., 9 inch) continuous cut into a patient's arm to harvest the radial artery also presents serious risks, such as severing the delicate superficial radiac and/or lateral antebrachial cutaneous nerves.
In an effort to avoid these risks, it has been proposed (and is currently practiced) to instead make two, transverse, 2-3 cm in length incisions—one at the patient's wrist, and the another 4 cm from the patient's antecubital fossa (see, e.g., Y. Terada et al., Endoscopic Harvesting of the Radial Artery as a Coronary Artery Bypass, Ann. Thorac. Surg. 1998; 66:2123-4, and A. Uchida et al., Endoscopic Harvesting of Radial Artery Graft for Coronary Artery Bypass, Ann. Plast. Surg. 1998; 41:459-463). Alternate loci for these two, tranverse incisions have also been proposed/practiced, including at 4 cm from the patient's wrist, and at the middle region of the patient's forearm (see Z. Galajda et al., Minimally Invasive Harvesting of the Radial Artery as a Coronary Atery Bypass Graft, Ann. Thorac. Surg. 2001; 72:291-3).
Although specific radial artery harvesting techniques may differ with respect to equipment used and/or approach taken, they generally entail (once the two transverse cuts are made) inserting a retractor within each of these incisions to lift the skin and tissue (i.e., the deep fascia) located directly beneath the skin, thus forming several skin bridges between the incisions, and defining subcutaneous space beneath the skin bridges.
Generally, any remaining deep fascia tissue is then transected to reveal the bracioradialis and flexor carpi muscles, which are pushed aside to expose the neurovascular fascia, which are transected to reveal the radial artery within loose areolar tissue. The areolar tissue is then displaced to allow the radial artery to be harvested (e.g., by hand, with one or more tools)
Regardless of the size and placement of the incisions that are made within the patient's arm, most radial artery harvesting techniques (including the Terada and Uchida techniques) necessarily rely upon the use of several instruments. Among these, generally, is an endoscopic apparatus, which provides visualization of the subcutaneous surgical field and, optionally, provides a lumen, through which tools may be introduced during the harvesting procedure, and/or through which the excised radial artery (or other tissue) may be withdrawn.
There are several notable drawbacks associated with using endoscopic technology for visualization of the subcutaneous space in connection with radial artery harvesting. First, the endoscope (or the display unit that depicts its image) provides a distorted visual perspective, which is a poor substitute for actual visualization of the surgical field by the naked eye. Second, compounding the first drawback, use of an endoscope provides for visualization of only a small portion of the subcutaneous space, namely, the area that is immediately in front of the endoscope. Third, illumination within the subcutaneous space created by this type of endoscope is also limited to the light emitted directly at the distal portion of the endoscope.
Because of these disadvantages, there is a significant learning curve to safely and efficiently practice this radial artery harvesting procedure.
Other drawbacks also are caused when attempting to use conventional equipment in connection with the skin bridging radial artery harvesting procedure. For example, because the skin bridges between the transverse incisions are quite long, it is difficult to sufficiently illuminate the subcutaneous space, especially when conventional, non-illuminated retractors are implemented/utilized.
Moreover, the area from which certain vessels are harvested may have smaller, narrower dimensions than the most other bodily areas within which vessels to be harvested are located. For example, a patient's arm (in which both the radial artery and the basilic vein are located) is comparatively narrower than his/her leg, in which the saphenous vein is located. As such, the subcutaneous space within a patient's arm is likely comparatively more crowded with instruments during the harvesting process, thus complicating the process and further prolonging the learning curve for safely and efficiently practicing radial artery harvesting.
Therefore, a need exists for a procedure that overcomes the aforementioned visualization- and illumination-related drawbacks, as well as the spatial limitations that individually and collectively plague conventional radial artery harvesting techniques and prolong the learning curve required for medical personnel to safely, yet expeditiously practice such techniques.